The present invention relates to an exhaust gas recirculation valve for metering exhaust gas flow to the intake of an internal combustion engine.
Exhaust gas recirculation (EGR) valves are used to control exhaust gas recirculation in internal combustion engines. Existing EGR valve assemblies include a valve positioned by an electrical solenoid to meter the exhaust gas which passes through the EGR valve assembly. The solenoid retracts the valve from a seat to increase recirculation of exhaust gas, and advances the valve toward the seat to reduce recirculation of gas. The seat is incorporated in a base assembly that mounts the valve on the engine manifold.
Existing EGR valves, such as set forth in U.S. Pat. No. 5,020,505 issued Jun. 4, 1991 to Grey et al. include a magnetic solenoid actuator that moves a valve member relative to a valve seat to regulate the flow of exhaust gas therethrough. During operation of EGR valves, the valve member may become encrusted with carbon or other exhaust material, interfering with the operation of the EGR valve. Build up of exhaust matter may lead to leakage of exhaust gas or otherwise interfere with the movement of the valve member, thus making it difficult to meet ever-tightening emission regulations for internal combustion engines, particularly after the engine and EGR valve have been used for a period of time.
One aspect of the present invention is a hydraulically actuated exhaust gas recirculation valve assembly for metering exhaust gas to the intake of an internal combustion engine. The exhaust gas recirculation valve assembly includes a base having an internal cavity with a control portion and a flow-through portion permitting flow-through of exhaust gas. The base has a hydraulic control port in fluid communication with the control portion of the cavity, and the control port has an inlet. A valve body is rotationally mounted within the base. The valve body includes a hydraulic control spool disposed within the control portion of the internal cavity. The hydraulic control spool generates a rotational force in response to a hydraulic pressure applied to the control port. The valve body further includes an exhaust gas control spool positioned in the flow-through portion of the internal cavity and connected to the hydraulic control spool and rotated therewith to selectively control flow of exhaust gas through the flow-through portion of the internal cavity.
Another aspect of the present invention is an internal combustion engine including a hydraulically actuated valve assembly for metering exhaust gas to the intake valve of the internal combustion engine. The valve assembly includes a housing having an exhaust gas inlet port operably connected to the exhaust of the internal combustion engine. An exhaust gas outlet port is operably connected to the intake of the internal combustion engine. A valve body is movably mounted within the housing and selectively meters the flow of exhaust gas between the exhaust gas inlet port and the exhaust gas outlet port upon movement of a valve body within the housing. The valve body is operably connected to a source of pressurized hydraulic fluid and configured to move for metering of exhaust gas flow upon application of hydraulic pressure to the valve body.
Another aspect of the present invention is a hydraulically actuated exhaust gas recirculation valve assembly for metering exhaust gas to the intake of an internal combustion engine. The valve assembly includes a housing having an internal cavity defining a generally cylindrical sidewall surface and having an exhaust gas inlet port in fluid communication with the internal cavity and adapted to be connected to the exhaust of an internal combustion engine. The housing further includes an exhaust gas outlet port in fluid communication with the internal cavity and adapted to be connected to the intake of an internal combustion engine. A valve body is rotatably mounted within the internal cavity and selectively meters exhaust gas flow through the housing. The valve body includes a sharpened knife edge disposed adjacent the sidewall surface, such that the knife edge removes exhaust gas deposits from the sidewall surface upon rotation of the valve body.
The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:
FIG. 1 is a partially exploded, partially fragmentary perspective view of a hydraulically controlled EGR valve according to the present invention;
FIG. 2 is a cross-sectional view of a first embodiment of the hydraulically controlled EGR valve of FIG. 1 wherein the valve body is hydraulically powered in first and second rotational directions;
FIG. 3 is a side elevational view of the EGR valve of FIG. 2;
FIG. 4 is a cross-sectional view of the EGR valve of FIG. 2 showing the hydraulic control spool taken along the line IVxe2x80x94IV, FIG. 2;
FIG. 5 is a cross-sectional view of the EGR valve of FIG. 2 showing the exhaust gas control spool taken along the line Vxe2x80x94V, FIG. 2;
FIG. 6 is a cross-sectional view of a second embodiment of the EGR valve of FIG. 1 wherein the valve body is hydraulically powered in a first rotational direction, and utilizes a spring to bias the valve body in a second rotational direction;
FIG. 7 is a side elevational view of the EGR valve of FIG. 6;
FIG. 8 is a cross-sectional view of the EGR valve of FIG. 6 showing the hydraulic control spool taken along the line VIIIxe2x80x94VIII, FIG. 6; and
FIG. 9 is a cross-sectional view of the EGR valve of FIG. 6 showing the exhaust gas control spool, taken along the line IXxe2x80x94IX, FIG. 6.